Low altitude bombing system and apparatus



Aug. 11, 1959 J. A. RYAN, JR

LOW ALTITUDE BOMBING SYSTEM AND APPARATUS Filed Sept. 15, 1955 5 Sheets-Sheet 1 INVENTOR. I JOH/Y H. 1876/) we.

BY I

' Armani-Y J. A. RYAN, JR

LOW ALTITUDE BOMBING SYSTEM AND APPARATUS Filed Sept. 15, 1955 Aug. 11, 1959 5 Sheets-Sheet 2 Aug. 11, 1959 Filed Sept. 15, 1955 LOW ALTITUDE BOMBING SYSTEM AND APPARATUS INVENTOR.

5 Sheets-Sheet 3 JOHN 6. E/H/V J16.

Aug. 11, 1959 J. A. RYAN, JR 2,393,809

LOW ALTITUDE BOMBING SYSTEM AND APPARATUS Filed Sept. 15, 1955 5 Sheets-Sheet 4 WLTJQSZ meal-r w -;w

INVENTOR. J0/7l7 '4. EYfl/V JE.

Aug. 11, 1959 J. A. RYAN, JR

LOW ALTITUDE BOMBING SYSTEM AND APPARATUS Filed Sept. 15. 1955 5 Sheets-Sheet 5 INVENTOR. JOH/Y F7. EYfl/Y JE.

WM. i N0 HTZOENEY? LOW ALTITUDE BOMBING SYSTEM AND APPARATUS John A. Ryan, Jr., Arlington, Va. I Application September 15, 1955, Serial No. 534,630 Claims. (Cl. 239-) (Granted under Title 35, U.S. Code' (1952), sec."266) The invention described herein may bemanufactured and used by or for the United States Government-for governmental purposes without payment to me of any royalty thereon.

This invention relates to an improved low altitude bombing system and apparatus for the release of high explosive devices and bombs from aircrafts, and ,primarily to an improved apparatus, system, and method of toss bombing of very high explosives above or on a selected target from a low'level approach-toward the target and providing a safe escape distance and maneuver for theaircraft after the released the explosive device or bom b, having for an'object the-accurate release and tossing of a high explosive device at a predetermined point in a flight pattern relative to the target, calculated in relation to the speed, altitude, and a selected pull up angle of the aircraft, including means for automatically releasing the bomb device at a predetermined 'angleof climb during the pull up.

A further object is the provision of a bombing system and apparatus for delivery of high explosive devices and bombs for accurate tossbombing thereof above, or on a selected target from a low level approach toward the target and providing a safe escape distance and maneuver for the aircraft following the releaseand tossing of the explosive device or bomb, having for a further'object the delivery of time delay fused types of high explosives, timed to explode above the target in relation to speed,

altitude, and a selected pull up and release climb angle,

including means for indicating to the pilot the time instant of release of the bomb device and the starting of the time for executing the predetermined escape maneuver, so that the aircraft will be flying at a safe remote distance from the bomb device and target area at the time of the explosion of said bomb device, and'moving in a direction away from the target, preferably Without crossing the projection of the explosive device or bombs trajectory on the ground.

A further object comprises an improved bombing system and apparatus for delivery of high explosive devices and bombs from aircrafts for accurate toss bombing of very high explosives above or on a selected target from a low level approach toward the target and providing a,

safe escape distance and maneuver for the aircraftfollowing the release of the explosive device or bomb Without crossing the projection on the ground of the explosive device or bomb trajectory having for a primary object the delivery of predetermined time delay fuzed types of high explosives timed to explode above or on the target in relation to the speed, altitude, and a selected pull up and climb angle of the aircraft from a predetermined or selected point to be crossed by theaircraft at a known distance from the target, including means for indicating to the pilot the time-for the precalculated rate of pull up during the approach together with means for automatically releasing of the bomb device at a predetermined angle of climb during the pull up at the precalculated safe escape distance from 3 the 'target area, including also pilot -signal means :to indicate when the release of the bomb takes place during the pull up constituting a signal for thepilot -to-' execute a pre'determined escape 'maneuver without 'crossingthe target area so that the aircraft will beat 'a safe remote distance from thebomb device at the time ofthe explosion thereof and flying in a substantially radial direction away from the target.

further'object is theiiprovision of an improve'd aircraft bombing system'in which'a preset-"adjustable timer or intervalometer-=device is provided in the aircrafttogether -with a normally cagable vertical gyroscope, in which the gyros'copeis uncag'e'd by'the pilot during the approach toward a selected target 5 prior to the crossing ofarselected: prominentgeographical reference point 'during the approach at a predetermined distance fromthe selected target, including :means under control of the pilot for simultaneously starting the intervalometer timing a cycle: and 1 the bomb 'fuze timing *cycle, in" which the first intervalometer control's a :pull up or climb signal indicating means for'thespilot, to 'determinethe time for execution of the" predetermined climb or pull up maneuver at apredeterminednumber of gs,--and includes release :means controlled by the vertical gyroscope for effecting: an automatic release of the bomb device at substantitally anytpredetermined or selected 'ang'le-ofclimb also including signal means' for indicating when the bomb has been "released and time for initiating I the predetermined escape maneuver in order *to'provi'de-a sufficient fuzed bomb devices by' ai'rcraft, I inwhich the-aircraft isfiown toward a seleotedi target at'a prescribed low altitude overia'zpreselected terrain inwhich some suitable initial permanentpoint or fixed geographical reference point is'present andifairly.easilyfdiscernable, preferably having a long "dimension perpendicular 'to' the 'flight path toward, and at a suitable remote distance from, the se-' lected target, forinstancefro-m between 3"to 6 miles, a settable timerror fuze mechanism being provided in" the bomb and preset before reachingthe initial point for determining the range between the initial-or prominent point and the desired point of explosion of the bomb device over'the selectedtarget, calculatedin time inaccordance with vthe 'expectedspeed of theaircraft from the initial or prominent pointto the calculated pull up point,rplus the pull upftime tothe climb angle, during the 'pull up,'at'which'the bomb is to be released, plus thettrajectory or travel time of the bomb from its release point to the point above or on the target-where the burst is totake place, an intervalometer or timer mechanism being also'provided in the aircraft Which is adjusted" prior .to reaching the initial or-prominent point to indicate the. calculated instant for the pull up for eifecting therelease-of the bomb device from the instant of passageof the aircraft over the initial or prominentpoint invterms'of' the expected ground speed of the aircraft, the system providing means under control of the pilot 'for simultaneously:initiating'both'of'the timers into operation just as the initial'point is crossed, including means fortreleasing the bomb automatically during the pull. up"

ata precalculated angle ofclimlz pwith the; pull .uppoint precalculated at a suflicient distance from the target, between the prominent point and the target, to permit the aircraft to execute a substantially 180 turn or an Immelmann, or a loop and be flying away from the target at a safe escape distance from the bomb device at the time that it is exploded by its timer.

. A further object is the provision of means under control of the pilot for interrupting the timing cycles of both timers and restoring them to their initial starting position at any time prior to the time of pull up and release of the bomb device.

In one form of the invention the distance :between the selected prominent geographical or initial reference point and the target is composed'of two time segments, one being the time from the initial point to the pull up point, plus the time required from the pull up" point to the bomb release point, and the other is the calculated trajectory time from the release point to the burst point over or on the target, this latter segment from release point being what might be termed as the safe escape time or distance. The timer in the explosive device is set preferably to include both time segments. Since the geographical location of the prominent or initial point with respect to the target will vary depending upon the selected target, while the pull up time plus the escape time period, can be considered at a substantially fixed minimum, for the particular explosive device employed, the first or variable segment is calculated by subtracting the second or minimum distance, or safe time factor plus pull up time from the total distance or time factor, from the initial point to the release point, plus the trajectory time of the released explosive device to the target. The resulting range segment can therefore be easily varied to suit the geographical conditions encountered.

Assuming that a conventional intervelometer is used which can be set for any time interval up to 24 seconds in intervals of .02 second, and that the bomb also has a suitable similar timer or intervalometer therein functioning as a time delay fuze device, then at 546 miles per hour the speed is 800 feet per second and .01 second error is 80 feet and .02 second error is 160 feet. A 4 g pull up at the assumed speed represents about 2241 feet or travel and this is precalculated and fixed, but may vary depending on the climb angle in the pull up where release takes place. The trajectory of the'bomb device after release depends upon an initial 800 feet per second, plus the fuze time in the bomb if the burst is to take place above ground and the trajectory time can be longer if release (climb) angle is increased. For instance, above 45 climb angle, the range may be shorter, although the time between release of the bomb and burst may be increased with safety if desired, also a change in the approach altitude will effect the maximum time of trajectory for a burst in the air at the same elevation above the target.

Assuming that the center of a selected target area from a selected prominent geographical reference point, such as a road, railroad, dam, or bridge running substantially transverse to the flight path toward the target is 17,542 feet, also that no wind is present and therefore no reduction or increase in air speed need be calculated, and calculating aircraft ground speed at 800 feet per second (546 mph.) and also assuming a 4g pull up from level flight to a predetermined climb angle of 20 where the bomb is automatically released is calculated, at a distance of, for example, 10,000 feet from the target, the 4g pull up distance in this instance to bomb release angle will cover 2241 feet ground range. Since total range distance from the initial point to the target is as sumed to be 17,542 feet the sum of the distance from the release point to the target is added to the 4g pull up distance and this total is then subtracted from the total distance between the target and the prominent or initial point, hereafter indicated as I.P., thus leaving a range distance of 5301 feet from the LP. to the pull up point and this is set on the intervalometer in the aircraft in the form of seconds and fractions of seconds, the intervalometer timing cycle being started by the pilot depressing the lbomb button as the aircraft crosses the LR, and as indicated, also determine the time for the initiation of the 4g, for example, pull up or climb, the bomb being released automatically at the selected climb angle as determined by the closing of electrical sector switch contacts in a vertical gyro, the intervalometer or timer in the bomb device or fuze being preset, preferably before take-off for the time period to include the time of flight from the LP. to the pull up point plus time from pull up point to the release point, plus the time of flight or bomb trajectory from the release point to the burst point, located at or over the target.

These time intervals are easily and conventionally calculated and tabulated, and therefore specific times are not given. However, for the example indicated above it would be 23,886 seconds and the timer in the bomb device is set for that time and initiated into operation as the aircraft crosses the I.P." simultaneously with the range timer for indicating the time when pull up point is reached. From the example given it will be seen that the time remaining from the initial point to the release point is 9.486 seconds.

Initial point to pull up point 6.626 sec. Pull up point to release point 2.860 sec.

Initial point to release point 9.486 sec. Calculated bomb flight or trajectory time from release point to burst point 14.40 sec.

Bomb device timer set at 23.886 sec. total.

Assuming that 14.4 seconds is considered a suflicient time to provide a safe escape distance for the aircraft by banking and executing turn, which in this example causes the aircraft to fly radially outbound from the expected burst point to elfect best escape, or by executing an Immelmann or a loop immediately following the bomb release, so as to be flying away from the burst point, at a distance, for the example given, of approximately 10,000 feet from the burst point over the target area. With faster aircraft, including modern jets the escape distance can be increased, or the calculated release point can be moved further from the target, or bomb devices of greater destruction power can be employed.

A further object of the invention is therefore a method and means for delivering a high explosive bomb device with greater accuracy over or on a selected target during a low level approach, Without requiring the aircraft to approach too close to or cross the target area.

A further object is the provision of means and a method of utilizing a prominent geographical land mark at a known remote distance from a selected target as a means for calculating a release point at which a bomb should be released from an aircraft flying at a predetermined speed and low altitude and tossed toward the target in order to produce a hit at the target, with sutficient time for the aircraft to fly to a remote safe distance from the burst of the bomb device without crossing the target area.

A further object is the provision of a bombing system in which selected target is approached at a predetermined ground speed and low altitude by flying across a selected prominent geographical point at a known remote distance from the selected target and presetting a timer means on the aircraft which is initiated into operation while passing directly over the prominent point to determine a predetermined elapsed time period during flight from the prominent point toward the target in which signal means operated by the timer indicates the termination of the selected time period and the instant when a predeofabombdeviceat a preselected climb angle, thesystem includingvertical gyroscope means having an adjustable climb angle signal indicating contact means incorporated therein, .and releasemeans operable by the climb angle signal, contact means. for releasing a bomb carried by the aircraft at the predetermined climb angle, incorpo rating. signal means: for indicating. when the predetermined .pull up bomb release or climb angle of said aircraft is reachedat apull up of the predetermined number of gs.

A.further object is the provision of a bombing system inwhich the vpilot must close a normally open control switch at. thetimethe aircraft crosses the prominent point andmustmaintain the switch closed throughout theapproach. toward thetarget up to the time when the bomb device 'is automatically released during .thepull up n;a selected target duringa flight path which is initially a.low level approach, andv includes means arranged to stop; the effective. timing cycles of the intervalometer and thebomb timer fuze or timer mechanism and returnthe timing mechanisms to zero, thereafter requiring-.;.a: completerepeat. cycle of the bombing system and another. tripover the prominent point in order to deliver the;bomb. at the target from a low level altitude and provide a safe escape for the aircraft after release of the bomb without crossing. thetargetarea or the projected: trajectory on the ground. of the trajectory of thebomb.

Other objects and. advantages will become apparent from. the following. description and accompanying drawings in which like parts are referred to by like reference characters inthezseveral figures.

Figure v1 isa diagrammatic side elevation of my improved. bombing method and system, the light full line indicating the trajectory of the bomb device after release of .a type of intervalometer or timer which may be used in the explosive device or bomb for fuzing the same.

Figure- 5 is-a somewhat diagrammatic top plan view of. a normally caged vertical gyroscope, incorporating the settable release contact means for effecting a release ofithe bombdevice at. any predetermined pull up or climb angle.

Figure 6.is afragmentary vertical cross sectional view through the portion of the gyroscope shown in Figure 5,

more clearly showing the adjustably settable contacts forestablishing the release impulse, and taken approximately onthe 1ine.66. inFigure 5 looking in the direction of thearrow, certain parts being broken away and omitted .for. clarity.

Figure 7.is a somewhat fragmentary vertical longitudinalsectional view of a portion of the normally caged vertical gyroscopeshown in Figures 5 and 6, the section being taken approximately on line 7-7 of Figure 6.

Figures 8, 9 and 10 are diagrammatic views showing a few modifications of the method employed in deliveringan explosive device on a selected target from a low level approach, while afiording a suflicient escape time or distance for the aircraft, after tossing the bomb device to be flying radially away from the target area at a sub stantial safe distance at the time the bomb device. explodes.

vReferring more particularly to the schematic wiring diagram shown in Figure 3, and Figures land 2, the operationis as substantially as'follows:

Preferably before take-off the distance G between some prominent geographical reference point A and a selected target B, as shown in Figures land 2, is determined and converted into time of flight from the prominent point- A to a selected point D for release of the bomb during a predetermined climb or pull up C-D" in relation to the calculated speed of the aircraft and altitude at the time the pull up C-D' is to be initiated. This time is cal culated to represent actual ground speed of the aircraft D and is divided into two segments or sections, the first section E'being the time of flight from the prominent, point A to the point of pull up C plus time from point C of pull up, for instance, at a 4gs pull up, to point D where release of the bomb is to occur, Since the time interval from point D of release of the bomb, plus the time of flight or trajectory F of the bomb for a given altitude and ground speed, in order to provide a safe escape time period and distance for pilot and aircraft, is substantially fixed, this time or distance F is subtracted from the total range time or distance G from the promi-- nent point A to the target B, leaving the aircraft flight time from the prominent point A to the pull up point 'C as a variable, calculated to suit the geographical relation. between the selected prominent point A and the target B, in any particular situation.

The vertical erectable gyroscope H employed is ofa.

conventional type for instance, known commercially as Cagable Vertical Gyroscope Model 167044, manufactured by Minneapolis-Honeywell. These commercial vertical gyroscopes are modified as shown and described hereafter to provide an adjustable segmental contact means or sectorswitch 10, adjustable for closing a bomb release circuit.

at any specified pull up or climb angle when these switch contacts are placed in the bomb release circuit.

The timer or intervalometer I, employed for indicating the pull up point C may also be of anyconventionah type, such as, for instance an'intervalometer which can be set to provide a circuit energizing electrical impulse after any desired number of seconds and fractional parts of a second, and an energizing electrical circuit means for initiating the intervalometer timing cycle by depres sion of a bomb button is provided. Onetype of con-I ventional intervalometer I, that may be used in the system isknown as a BlO'interval'omete'r (ABRAMS) disclosed! in U.S. Air Force publications TO -l0A5672, T echni cal Order l0A56 7-'3, andTechnical Order lOA567-4,.

all dated November 15,1951. These-intervalometers are.

adjustable to cover a time period up to 24 seconds in intervals of .2 second.

With the vertical'gyroscope H erected to vertical.

(Figure 3) and the timer or intervalometer I, set for the calculated flight time from the prominent point A to the pull .up pointC, gyroscope bomb release segmental contacts 10. of the sector switch in the gyroscope Hset for circuit closing contact at the calculated pull up or climb angle K. (Figure 1.) to effect the bomb release, and the timer or intervalometer I in the bomb set for atiming periodto include thecalculated flight time from the prominent point A to the pull up point C, plus flight time from the pull up point C to the bomb release point D,.

plus the time of .flight F or trajectory of bomb from the release point D to the burst-point B" with respect to theselected target B, the pilot, several minutes. prior to crossing the prominent pointA at the desired low altitude toward the target, for instance 600 feet, conditions the.

apparatus shown in Figure. 3 for operations in substantially the following manner:

The sight change-over switch 11 is closed by moving the same from. full line to dotted line position. This energizes relay 12 to move the contactsthereof from matically at H, and somewhat in more detail in Figures 5, 6 and 7, with the climb angle closing contacts 10 or sector switch mechanism illustrated more in detail in Figures 6 and 7. The gyroscope inner and outer gimbals are normally erected by any suitable erecting mechanism. Energizing transformer 17 closes the electrical circuits to the two erection motors 19 and 19 for the outer and inner gimbals of the vertical gyroscope H.

Closing relay contacts and 16 of relay 12 energizes the potentiometer coils 22 and 23 of potentiometers 22 and 23 on the inner and outer gimbal signal pick-off means to adjust a pitch or climb and roll indicator 24 at the pilots station to check or indicate the respective relative roll and pitch positions of the inner and outer gyroscope gimbals relative to the altitude of the aircraft, and also to indicate the roll and pitch attitude of the aircraft after the gyroscope is uncaged. Adjustable resistances 25 and 26 are interposed in the pitch and roll indicator input circuits for adjusting the pitch and roll indicator 24 at the pilots station to zero, either while the gyroscope H is erected, or just after it is released to allow for any change in flight attitude of the aircraft at the time it passes over the prominent point A toward the target B.

The LABS (Low Altitude Bombing System) start switch 27 is now closed by moving the same from full to dotted position to feed a +28 v. D.C. to the terminal of the intervalometer I, starting the intervalometer motor. This circuit is connected through the normally closed contacts 28 and 29 of the relay 30 to light the reticle lamp 31 preferably in the pilots gun or bomb sight, or it may be a signal device on the pilots instrument panel, indicating to the pilot that the device is conditioned for operation.

Another preliminary step requires the closing of the LABS gyroscope release switch 32 by movement thereof from full to dotted position, thus releasing the gyroscope H in zeroed position relative to the attitude and flight path of the aircraft at that time.

Opening of the caging switch 32 to the caged or dotted line position opens the caging circuit to deenergize the holding solenoid 34. With the caging circuit closed the device is now in released conditions and ready for subsequent control and indicating operations.

The aircraft should be approaching the prominent point A at the prccalculated (ground) speed and low elevation in the selected flight direction toward prominent point A and the selected target B.

Just at the instant that the prominent point A is crossed the pilot presses the bomb button 35 to close the bomb button switch and should keep it depressed until the bomb is actually released. Closing of the bomb button switch 35 by the pilot feeds a +28 V. DC. to conductor 36. The jumper wire 37 from this line 36 lights a warning or signal light 38, preferably on the pilots instrument panel to indicate that the lead 36 to the gyro sector switch K or contacts -10 are energized, and that the timing cycle has started. The sector switch K in the vertical gyroscope H is open however at this time and will not be closed until a pull up to the precalculated climb angle is made at the prescribed subsequent time previously set into the intervalometer I. Depression of the bomb button 35 simultaneously energizes the relay 39 through wire 39' moving relay contacts to close contacts 40 and 41, as seen in dotted line position, to close a timing cycle starting electrical circuit over conductors 42 and 43 to the intervalometer I, starting the intervalometer timing cycle, and to the intervalometer 1 starting the bomb fuze intervalometer timing cycle.

With the bomb button 35 held depressed the pilot continues on course toward the target B. At the end of the precalculated timing cycle the timing contacts of the intervalometer I close, sending an electrical signal impulse from terminal 43, wire 44, across normally closed contacts 45-46 of relay 47 to the contact 48 of relay 30, a shunt or holding circuit beingestablished between contact 48 and relay coil 49 of relay 30, closing contacts 28 and 48 and 50 and 51, and separating contacts 28 and 29 of relay 30, the latter extinguishing the reticle lamp 31. Closing contacts 28 and 48 of relay 30 close the circuit torelay coil 49 of relay 30, and acts as a holding relay circuit, so long as the bomb button 35 is maintained depressed.

Closing of contacts 51 and 40 of relay 30 energizes relay coil 52 of relay 47 to shift the contacts of this relay 47 to dotted line positions, closing contacts and 61 thereof and breaking the contacts 45 and 46 thereof.

Closing contacts 60 and 61 of relay 47 establishes circuits to the conductor 53 connected to terminals 54, 55 and 46 of relay 57. Coil 62 of relay 57 is energized by the closing of the contacts 10 of sector switch K, during the subsequent pull up or climb at the time the reticule.

light 31 goes out.

The separation of contacts 45 and 46 of relay 47 de energizes the initial energizing circuit in relay 30, however, this relay 30 remains closed due to the holding circuit established through contacts 28 and 48 of relay 30. The opening of contacts 28 and 29 of relay 30 extinguishes the reticle lamp 31 which is a signal for the pilot to immediately execute the prescribed pull up indicated at CD in Figure 1 at the prescribed number of g7S-,

As the pilot makes the prescribed pull up at the prescribed number of gs and reaches the climb angle K as set in the gyroscope H, for instance as shown in Figures 3 to 7, the sector switch contacts 10 close.

The closing of the sector switch contacts 10 energizes the bomb release circuit 59 and again lights the reticle lamp 31, indicating that the bomb device has been released and that the prescribed escape pattern or maneuver D-D', Figures 1 and 2, should be immediately executed.

Closing of sector switch contacts '101(l and 56, feeds +28 V. DC. from bomb button contacts 35 through branch conductor 59' to energize the coil 62 of relay 57, closing the contacts 54 and 63, 55 and61 and 56 and 64 of relay 57 to establish release circuit through closed sector switch contacts 10, 10 and 56 and 64 of relay 57 to energize release circuit through conductor 65 to the bomb release mechanism or shackles.

Closing contacts 54 and 63 of relay 57 establishes a holding circuit for relay 57, holding this relay closed, so long as the bomb button 35 is maintained depressed.

Closing of contacts 55 and 61 of relay 57, again closes the circuit to reticle lamp 31, again switching it on, indicating that bomb has been released, while closing of contacts 5'6 and 64 closes the circuit to an electrical bomb release device or bomb shackles, automatically releasing the bomb during the pull up, at the prescribed angle of climb.

The pilot can now release the bomb button 35, and should execute a bank and turn DD of approximately -180 while the flight or trajectory of the tossed bomb describes an arc D-B, so to speak, toward the target B, so that the pilot and aircraft are now travelling substantially radially away from the target B, at a safe distance from the target and the bomb, when the timing mechanism or fuze in the bomb device explodes the same. The pilot may continue his upward climb after release of the bomb if it is desired to execute an Immelmann turn maneuver, instead of a bank and turn, how ever, this would increase the altitude of the aircraft materially, which might not be desirable in the event of heavy anti-aircraft defense on the ground. He may also complete a loop to be flying away from the target at a lower altitude.

It should be mentioned again that the bomb timer or fuze is preferably started by the initial depression or pickling of the bomb button, and this timing mechanism is arranged to discontinue and reset automatically to ass ss zerojat any time thebomblbutton is released,-up:to;the, actual release of the bomb'dfiringihlepresdribd up, after which the bomb' timer would continue ande xplode". the bomb for the initial time interval set, startingfromthe time when the'pilot first depressesthebombbutton35 andkeeps it depressed.

A slight modification of-the bomb timer fuzedevice iscontemplated, in which the bomb timer, although set before take-01f, is set for the time interval. of' fligh'tor.

trajectory of the bomb from the release point D in. the climb or pull upto the burst point B over (or on) the target B. In this instance the timing, cycle for. the bomb intervalometer or fuze device would be initiated by the actual release of the bomb which closes the bomb timer or fuze circuit, and, is connected'inthe release circuit. so as to be closed to start the bomb timer with the closing of 'the contacts 56 and.64 of the relay 57 as. the release mechanism or bomb shackles are actuated to releasethe bomb.

As before mentioned the improved bombingsystem and.

method require that the bomb button 35 b'e depressed or pickled just as the aircraft crosses over the prominent'point A and maintained depressed throughout the.

entire ensuing time or until the-reticlelightgoes out, and,

comes onagain asthebomb-device is released. Any release .of the bomb button restores the cycling mechabutton directly over the prominent pointA.

Release of thebomb button 35 'deenergizes relay 39.. Openingcontacts 40 and 41. ofrelay 39' to break the timer starting circuit to the intervalometer Lthrotugh conductor, 44C and extinguishing, the warning lampv 70 onthe pilots instrument panel. The holding circuit contacts 28 and..48 of relay 30 will be deenergized; even-- after the intervalometer I timing. cycle has been completed, and. even duringthe pull up, if the bomb buttonis released before the release point .D is reached. Opening of the bomb button switch' 35 will; deenergize; the:

contacts 60 and 61 of relay 47 to, open contacts. 54 and 63 to open the circuit to the relay coil'62 'and'its' holding.

circuit 59', thus preventingflthe relay contacts. 54 and 63, 64rand 56 and '55 and61 ofrelay 57 from closing. Thisrestores the system to zero, and deenergizesathe bomb fuze or timer 1' and also restores the same to.

zero, makingit necessarytoreturn and repeat the, system procedure, by recrossing the prominent point, depressing,

the bomb button 35 at time of crossing, and holdingthe button. 35 depressed until the pull up is' made and-the. It should be particularly mentioned that the deenergizing vof the circuit tothe-bomb fuzingl bomb is released.

intervalometer at any time prior to the releaseand drop:

ping of the bomb causesthe bomb intervalometer timing circuit contacts to also be restored to zero. As the bomb is released in this instance this closes the intervalometercontrol circuit for or in the intervalometer I. andthe same will continue to function after release to 'explode' the bomb at the, expiration of the time period, as set'into the bomb fuzing intervalometer I;

Referring to Figures 5, 6- and 7'the adjustable sector' switch mechanism K associated with the vertical gyroscope H for determining the bomb release 'pull'up angle 65 axis of the outer gimbal 72 is indicated at 71 and is isshown in somewhat greater detail in which the tilt disposed parallel to the pitch axis of the aircraft. The

outer gimbal 72 carries a lug member-or arm 73 fixed thereon on-Which a movable contact or wiper contact .74 is fixed, the wiper contact -74 being ininsulated relation to the arm 73. This wiper 74 remains fixed in space With the outerv gimbal 72relative to theachange in pitch of the aircraft during the pull up orclimb maneuver from the pull up point C (Figure'l).

The complemental sector switchblades, indicated; at

- channel 77 in the frame'portion 75.

10; are adjustably disposed on: or carriedby the gyro-- scope-supporting frame or base 75 so that when theclimb angle ofthe aircraft is increasedto the set climb anglethe contact blades 10 simultaneously engage the wiperelement 74 and close the bomb release circuit, conditioning the bomb release mechanism for operation throughthe relay 57 at the-desired climb angle K.

The frame 75 carries a rotatably adjustable-partial ring or plate 76 which is slidablyadjustable in an annular The plate 76- is provided with a peripheral gear or rack 78, substantially as shown,nmeshing with an adjustment pinion 79, fixed. on .a verticalshaft 79 carried in suitable bearings ina bracket member 80 supported atthe top of the frarnepor-- tion 75f. p I

An indexing dial or plate 81 is fixed'on the shaft'79 for the pinion 79-by a projecting pin 81' extendingupwardly from a flanged portion of the pinion shaft structure.

The two resilient segmental contact arms 10-10 are fixed to the ring plate 76 in laterally spaced parallel v overlappingrelation as shown, being insulated from the plate 76 and from each other with their-contact ends. disposed substantially in a radial plane from the outer. gimbal tilt axis 71. v A circular insulating supporting v structure 82.is fixed to, and extends axially from the' adjustable plate 76,- being formed with annular peripheral channels 83 and .84. In the base-of the channels 83 and 84. are contact strips or slip rings, each ring being connected to one of the contact blades 10-10, and Wiperelements or contact brushes 8585 on the frame-75 are" located in bomb releasecircuit toth'e relay 57 (Figure 3) extending :from the segmental contacts 1010.- The inner'end of the.circular-supporting structure82 carries a circular'adjustable index ring 86 having suitable dive and "climb angle indicaS7 'and 87 imprintedin distinctive colors thereon asshownin Figure 4, being adapted. to register with a fixed index line or arrow 88 (Figure: 5) on abracket 90 extending from the frame 75.". Thesmaller indexing dial 81 also has cooperating angle indicia 890m its upper face registering with'the index' line. 8.

The ratio of the pinion 79 to thelarge partial ring gear 78 is preferably such that one rotationof the-pinion 79 causes rotation-(10 degrees) of the largeindexing ring 86, the small index plate 81 being divided as shown, into. 10 degrees each degree :being subdivided in .02 degree divisions. The large gear ring indicia 87 is indexed in divisions of 5 degrees as shown in Figure 5, and is observed through the window 91, being adjusted by a stem' 92 carried on a removable plate portion 93 of the'case, the stem.92 being slotted at its upper end'at 94 -and-hav-- ing a.flan-ged lower end notched at 95 toreceiW/e and engagethe pin 81, forming a driving connection between thestem 92 and the pinion 79. A lockor jam nut 96 I is threaded on the adjusting stem supporting split guide tube .97, carried by the cover plate 93.

The adjustable plate 76 -is frictionallyheld in its'ad justed positions on the frame portion 75': by a clamping plate 98, forming one side of the channel 77 with a friction washer 99'therebetween, the plate 98 being retained to provide the desired friction pressure by the clamping screws 100.

The large circular indexing ring86 is also adjustable initially by'the provision of a flange portion 86 which is clamped between the circular shell or, barrel 82 and the clamping partial ring 86 and retained in the adjusted position bythe clamp screws 86 Once the initial adjust- ED161111 is made to dispose the contacting relation of the two contact blades 10 in proper relation to the degree indicia 87 and 87 on the indexing ring 86 no further relative adjustment of these parts should be necessary.

In adjusting the gyroscope-contacts Ill-+10 for the selected pull up or climb angle K (Figure 1), the climb angle indicia-87 is-utilized and-is preferably inscribed in white. A second set of indicia is inscribed on the dial ring 86 and on the index plate or disk 81 in a different color, for instance red, as indicated at 87 on the dial ring 87 and at 89 on the index plate 81. These red indicia marking 87* and 89 control the setting of the contacts -10 for closing at any prescribed dive angle, and are not used, however, in carrying out applicants bombing method and system.

Preferably, before take-01f the precalculated climb angle is set substantially as follows. The gyroscope H employed, as before mentioned, is a normally caged type so that the outer and inner gimbals 72 and 72 are normally caged normal to each other with the rotor spin axis 72 preferably vertical and perpendicular to the normal pitch axis of the aircraft and the outer gimbal axis 71 disposed perpendicular to the flight axis and parallel to the roll axis. This disposes the inner gimbal tilt axis 72 in a plane perpendicular to the pitch axis 71 and in a plane parallel to roll axis of the aircraft with the rotor spin axis disposed in a plane perpendicular to the flight axis.

With the gyroscope caged a screw driver bit is inserted in the slot 94 and rotated to adjust the climb angle adjustment shaft 92. As the screw driver is turned, ob-

serving the registration of the white pull up or climb angle indicia 89 and 87 through the window 91 until the selected pull up angle comes into register with the index line 88. The contact blades 10 are now set at the prescribed climb K (Figure 1) at which the bomb release mechanism, through relay 57, can be energized to release the bomb in carrying out the prescribed bombing method. The contacts 10-10 being thus in angular relation to the wiper contact 74 on the adjustable insulated ring 76 the selector switch K, the circuit 59 will be open until the climb angle indicated is reached during the pull up, following, of course, the conditioning operation of the other relays 12, 39, 30, 47 and 57, in the sequence as set forth in describing Figure 3.

One form of mechanical timer or intervalometer fuze device for exploding the bomb device at the desired time interval which can be employed is somewhat diagrammatically shown in Figure 4, in which the electrical conductor wires 101 and 102 extend to the explosive squib 103 for bomb device 104. Contacts 105 and 106 are provided which are normally open, being closed by a projecting pin 107 on an arm 108 which is loose on shaft 109, the arm 108 carrying an actuating gear 110 and coil spring 111 for urging the arm 108 in the direction 113 and toward the settable stop arm 114 pinned on setting shaft 109, the shaft being settable for any time interval desired by knob 115, the knob being splined or pinned on the shaft 109. A pointer 116 is provided which cooperates with an index dial 116 for indicating the interval of time or fuze period selected. The reference numeral 117 denotes a motor which is energized simultaneously with intervalometer I for determining the pull up period. The motor 117 could be of a clockwork type clutched in by the solenoid 118 if desired.

When circuit is supplied to the solenoid 118 and the motor 117 is energized, a clutch shifter 119 is actuated to engage a clutch 120 and cause rotation of the arm 108 and movement of the pin 107 away from the settable abutment stop arm 114 and toward the spring blades 105 and 106 contacts. When the pin 107 impinges the contact blades 105 and 106 forcing them together the circuit to the primer or squib 103 is closed to explode the bomb device 104.

Current is supplied by a battery 121 and any interruption in the current in the motor circuit 122, before the bomb is released, permits the spring 116 to disengage the clutch 120, and the spring 111 will reset timing cycle, if it occurs before bomb is released.

When bomb device I is released from the aircraft the bomb intervalometer circuit from the aircraft isbroken, of course, however the battery 121 is simultaneously automaticallyconnected to the motor 117 to continue to energize the motor without interruption and explode the bomb at the end of the timing cycle. This may be accomplished by providing a pair of withdrawablc contact strips 124 for the energizing circuit from aircraft. These strips 124 are thin and faced on one side with insulation 124 to open or separate the contact blades 125 in the circuit from the battery 121 from the contact blades 126 in the circuit which are connected to the motor 117.

As the bomb device I is released and dropped the separating contact bars 124-424 are withdrawn from between the complimentary contact blades 125 and 126 allowing the contacts 125 and 126 to first close on the tapered ends of the bars 124 (below the insulated portion) and as they are further Withdrawn or pulled out from between the contacts 125 and 126, the contacts 125 and 126 will engage each other without interruption in the motor circuit, closing the second energizing circuit from battery 121 to the motor 117, independently of the former aircraft energizing circuits. The timer or mechanical fuze device will now continue to function until motor 117 rotates the arm 108 sufiiciently to impinge and close the contacts and 106, firing the squib or primer 103 to explode the bomb device 104.

Under these conditions the bomb intervalometer timing cycle is initiated by the pilot, through the wire 42 and 43 shown in Figure 3, simultaneously with the initiation of the intervalometer I, by the closing of the bomb button or switch 35, at the time the prominent geographical reference point A is crossed (Figure 1).

Release of the bomb button or opening the switch 35 at anytime before the bomb device 104 is dropped resets the bomb timer fuze device shown in Figure 4, similar to the resetting of the intervalometer I.

Breaking of the circuit to the conductor wires 42 and 43 deenergizes the clutch engaging the holding solenoid 118, after which the clutch release spring 118 disengages the clutch 120, allowing the tortion spring 111 to return the abatement 107 (and its supporting arm 118) back against the settable timing stop arm 114, fixed on the time interval setting shaft 109.

Closing of the contact springs and 126 connect the end terminals of the battery 121 to the motor 117 so that the motor, formally driven by current from the wires 42 and 43 will now be driven directly by the battery 121. A suitable reduction gear train drive is interposed between the motor 117 and the timer drive gear 110.

In Figure 8 the selected target is indicated at B and the pull up point at C is selected directly above the target. In this instance the pull up point becomes the initial point at which the timer for the bomb device is started by the depression of the bomb button, the climb angle bomb release contacts having been set to close and release the bomb device at a calculated angle of climb which is slightly greater than 90, so that upon release, with the pilot starting his pull up from a point directly above the target at a predetermined calculated number of gs and continuing in order to execute an Immelmann.

The trajectory of the bomb device will be upward, backward, and then downward toward the target, with the aircraft passing under the bomb device. In this instance the intervalometer for timing the flight fromthe initial point to the pull up point would be set at zero time (or not used).

In Figure 9 the timing for indicating the pull up instant is also initiated by the pilot when passing directly above the target C, and the maneuver is substantially the same as in Figure 8, the primary difference being that the pilot, instead of executing an Immelmanu now flies an inside loop, the release of the bomb device occurring at the preset climb angle (which is greater than 90). The aircraft is looped under the tossed bomb device while the bomb device is tossed vertically and slightly backward.

then falling toward the target, as the aircraft is. escaping iii a direction radially away from-thetarget area;

In Figure 10, however, both intervalometers' are usedi However, the initial point and (point directly above) the-targetcoincide. The'initial point is indicated A and. thepull'up 'signal'timer is set for a calculated distance from-E 'to the pull up point C and the .climb angle bombrelease contacts are set for a calculated release or climb angle that is somewhat greater than in Figures 8 and-9*so that the expected upward and backward toss oft the-bomb device will have a trajectory directed towardj the target-located below the initial pointA In this'case the-bombdevice timer is started preferably at the initial* point'A and is timed to explode at the end of its expected or' calculated trajectory above, or on the target; The. aircraftylike that in Figure 9, executesra tight inside loop; under'the upwardly tossed and rearwardly tossed bomb device.

Another-modification which is not shown involves setting-the'release contacts for a climb angle of 90 and calculating the pull'up point' (from the initial point) and the 'number' of gs required for the pull up flight path suflicient todispose the release point directly above the. target; The bomb device, upon release, would then "be" tossedvertically upward and fall directly (vertically) back toward or on'the target and the aircraft would bring a (predetermined) choice of continuing the pullupinto an Immelmann or completing the loop below the level ofthe-upwardlytossedbombdevice, so as to be flying away from thebomb device and target ata low 'level' when timerforthe bomb device initiates the explosion above or o'n-the-target,"or if an'impact'fuze is used, at the time the bomb device strikes the target.

While the above description and accompanying drawings setforth oneembodiment of the invention-it is not intended to'limit the scope of the inventionto-theexact details-asdescribedand illustrated but only by the scope of -the-appended claims, and any changes and modificationsahatcome within the scope of those claims;

I claim:

1-. A low-altitude bombing system fora bombing aircraft comprising, a normally cageable vertical gyroscopehaving-a'supporting frame fixed in the aircraft, an outer 3 gimbal journalled on said frame for tilt on an axis parallel to'the pitch axis of the aircraft, an inner gimbal tiltable inthe outer gimbal on an axis perpendicular to; said outer gimbal tilt axis, a rotor journalled' in theinner gimbal onan axis perpendicular to said inner gimbal axis, spring actuated caging means for -nor-mallycaging said inner and outer gimbals normal to each other, a-"stepping relay-uncaging device for disengaging saidcaging means, angularly adjustable contact means carried by said frame for angular adjustment about said outer gimbal tilt axis, climb angle indexing means carried by thereforconnected to said contact means, bomb release i means operatively connected to said relay means, pull up signal means in the aircraft for indicating the time instant for. initiating the pull up, an intervalometer device carried by the aircraft for closing said pull up signal means at the end of its timing cycle to indicate the instant for pull up,. relay means including an energizing circuit for. initiating said intervalometer into operation;

manually operable relay circuit closing means for closing said. last relay means to start the intervalometer timing cycle; and .means for deenergizing said last mentioned relay= means when said manually operable relay circuit closing means is opened.

2;,Apparatus as claimed'in claim 1 including a bomb,

device carried 'by and adapted to be released from the aircraff'by said bomb release device, a second intervalometer device carried by said bomb device adapted to be set for'a time interval exceeding the time'in-terval setting of thefirst mentioned intervalometer relay'means, an energizing circuit electrically connected to the first intervalometer timing cycle initiating circuit' whereby both of'said intervalometers are initiatedintooperation simultaneously and means for deenergizing and resetting said second intervalometer to zero automatically at any time prior to the closing of said gyroscope contacts. when said manually operable relay circuit closing means is opened.

3. In an improvedlow altitude aircraft bombingsyse tern for. lobbing a time fused bomb device-on a selected target 'at a predetermined air speed, low altitude and. distance from a selected targetsuificient forthe aircraft to turn and escape to aremote safe distance from the target by the time the bomb device reachesthe target; in which a.direct predetermined flight directiontowaldf the selected target is established which transversely. crosses a prominent elongated geographical land mark. reference point'at a :known remote distancev from the target which exceeds the time of trajectory'of saidbomb device Whenreleased from the aircraft during a pull up. ata'predetermined number of gs from a predeterminedl lo'w altitude and airspeed at a predetermined angle of: climb, suflicient to enable the aircraft to execute said. predetermined turn immediately following release of the, bomb device and be flying away from the target at said' safe remote distance by the time said bomb device. reaches the target area; said system-comprising; a bomb'. device; an aircraft releasably carrying the said bomb device, a preset timer carried by the bomb device and: set for exploding the bomb device at the termination of. a time period equal to the time of flight of the aircraft; between the instant of crossing of said "referencepointl and the instant of releaseof said bomb device plus the time of trajectoryof the bomb device between said instant. of release and the target; a second preset signal timer. carried by said aircraft preset for the time, of flight from the instant of crossing said reference point to the. point, of pull up for indicating the instant time for saidlpulll up for the aircraft from the crossing of saidv reference point; single means for simultaneously initiating both of. said timers into. operation at the instant of crossing said. reference point, and means carried by the aircraft fo'r'releasing said bomb device automatically at said predeter mined angle of climb only after the termination of the;

time interval determined by said second signal timer; and means for interrupting the timing cycle of .bbthof. said timers at any time prior to the termination of the. timing cycle of said second signal timer after said second timerhasbeen initiated into operation.

4. In a low altitude aircraft bombing device as set forth. in claim 3 in which the means for initiating. said. timers into operation includes an energizing circuit and: a manually operable switch means for closing said ci-r-.

cuit at the instant that said reference point is. crossed;.. means, for normalizing said circuit and automatically resetting said circuit and both of said timers at any time.

toward the target and closing of the switch means again, above said reference point and maintaining said switch means closed from the time of crossing of said reference point to said pull up and point of release of the bomb device in order to effect a release of the bomb device following the crossing of said reference point.

5. A low altitude toss bombing system for a. bombing aircraft comprising a normally cageable gyroscope havmg, 1

a supporting frame fixed in the aircraft, an outer gimbal journalled-on said frame for tilt on an axis parallel .to, the pitch axis of the. aircraft, an inner gimbal tiltablein;

said outer gimbal on an axis perpendicular to said outer gimbal tilt axis, a rotor journalled in said inner gimbal on an axis perpendicular to said inner gimbal axis, caging means normally caging said inner and outer gimbals normal to each other, an uncaging device for disengaging said caging means, angularly adjustable contact means carried by said frame for angular adjustment about said outer gimbal tilt axis, climb angle indexing means carried by said frame for adjusting said contact means angularly about said frame from a fixed reference point to any selected predetermined climb angle, cooperating contact means fixed on said outer gimbal for establishing circuit closing contact with said first mentioned contact 7 means when the aircraft puls up and reaches said predetermined climb angle, an energizing circuit therefor connected to said contact means, bomb release means operatively connected in said energizing circuit, pull up signal means in the aircraft for indicating the time in-' stant for initiating the pull up, an intervalometer device carried by the aircraft for actuating said pull up signal means at the end of its timing cycle to indicate the instant for pull up including an intervalometer timing cycle initiation energizing circuit for initiating said intervalometer into operation, manually operable circuit closing means for closing the last mentioned energizing circuit to start the intervalometer timing cycle, and means for deenergizing said last mentioned circuit and returning said intervalometer to zero when said manually operable circuit closing means is opened.

6. Apparatus as claimed in claim Sincluding a bomb,

device carried by and adapted to be released from the aircraftby said bomb release device, a second intervalometer device carried by said bomb device adapted to be set for a time interval exceeding the time interval setting, of the first mentioned intervalometer device, a second inteiyalometer timing device energizing circuit electrically connected to the first intervalometer timing cycle initiating circuit for initiating both of said intervalometers into operation simultaneously,'and means for deenergizing and resetting said second intervalometer to zero automatically at any time prior to the closing of said gyroscope contacts when said manually operable circuit closing means is opened.

7. A low altitude aircraft high explosive bombing apparatus for bombing a selected remote target on a bombing run directly toward said selected target which transversely crosses an elongated geographical landmark reference point at a predetermined flight time from the target which is in excess of a predetermined safe escape distance from the target at the time the bomb device is exploded at the target following a pull up and release of the bomb device at a predetermined low altitude, speed, and angle of climb suflicient to permit the aircraft to turn and fly to said safe remote distance from the target by the time the bomb device reaches the target, said apparatus comprising; a bombing aircraft; a high explosive bomb device releasably carried by said aircraft, pull up signal means carried by said aircraft; settable time controlled means carried by said aircraft for operating said pull up signal means to indicate a pull up signal to the operator of said aircraft; settable bomb release means carried by said aircraft for releasing said bomb device during said pull up at a predetermined angle of climb following the actuation of said pull up signal means by said settable time control means in which said settable time control means includes an intervalorneter and manual means for initiating said intervalometer into operation at the instant of crossing said prominent reference point in a bombing run toward the target, including a second settable time controlled intervalometer for exploding said bomb device, set for a time period equal to said time of flight from said prominent point to said pull up point plus the time of flight from said pull up point to said release point at said angle of climb at a predetermined number of gs plus the trajectory time of said bomb device from said release point to a burst point at the target, including means for simultaneously starting both of said intervalometers including a common intervalometer starting circuit therefor and an energizing bomb button switch for said circuit adapted to be closed by the pilot at the instant of crossing said prominent reference point in a bombing run toward the target.

8. A low altitude aircraft high explosive bombing apparatus for bombing a selected remote target on a bombing run directly toward said selected target which transversely crosses an elongated geographical landmark reference point at a predetermined flight time from the target which is in excess of a predetermined safe escape distance from the target at the time the bomb device ,is exploded at the target following a pull up and release of the bomb device at a predeterminedlow altitude, speed, and angle of climb sufficient to permit the aircraft to turn and fly to said safe remote distance from the target by the time the'bomb' device reaches the target, said apparatus comprising; a bombing aircraft; a high explosive bomb device releasably carried by said aircraft, pull up signal means carried by said aircraft; settable time controlled means carried by said aircraft for operating said pull up signal means to indicate a pull up signal to the operator of said aircraft; settable bomb release means carried by said aircraft for releasing said bomb device during said pull up at a predetermined angle of climb following the actuation of said pull up signal means by said settable time control means, in which said settable time control means includes an intervalometer and manual means for initiating said intervalometer into operation at the instant of crossing said prominent reference point in a bombing run toward the target, including a second settable time controlled intervalometer for exploding said bomb device set for a time period equal to said time of flight from said prominent point to said pull up point plus the time of flight from said pull up point to said release point at said angle of climb at a predetermined number of gs plus the trajectory time of said bomb device from said release point to a burst point at the target including means for simultaneously starting both of said intervalometers including a common intervalometer starting circuit therefor and an energiz ing bomb button switch for said circuit adapted to be closed by the pilot at the instant of crossing said prominent reference point in a bombing run toward the target, including means in said energizing circuit controlled by said bomb button; arranged to open said circuit upon release of said bomb button; and means for restoring both of said intervalometer timing devices to zero when said energizing circuit is opened.

9. A low altitude aircraft high explosive bombing apparatus for bombing a selected remote target on a bombing run directly toward said selected target which transversely crosses an elongated geographical landmark reference point at a predetermined flight time from the target which is in excess of a predetermined safe escape distance from the target at the time the bomb device is exploded at the target following a pull up and release of the bomb device at a predetermined low altitude, speed, and angle of climb sufficient to permit the aircraft to turn and fly to said safe remote distance from the target by the time the bomb device reaches the target, said apparatus comprising; a bombing aircraft; a high explosive bomb device releasably carried by said aircraft, pull up signal means carried by said aircraft; settable time controlled means carried by said aircraft for operating said pull up signal means to indicate a pull up signal to the operator of said aircraft; settable bomb release means carried by said aircraft for releasing said 'bomb device during said pull up at a predetermined angle of climb following the actuation of said pull up signal means by said settable time control means, in which said settable time control means includes an intervalometer and manual. :means for initiating said intervalometer into operation at the instant of crossing said prominent reference point in a bombing run toward the target, including a second settable time controlled intervalometer for exploding said bomb device set for a time period equal to said time of flight from said prominent point to said pull up point plus the time of flight from said pull up point to said release point at said angle of climb at a predetermined number of gs plus the trajectory time of said bomb device from said release point to a burst point at the target including means for simultaneously starting both of said intervalometers including a common intervalometer starting circuit therefor and an energizing bomb button switch for said circuit adapted to be closed by the pilot at the instant of crossing said prominent reference point in a bombing run toward the target including means in said energizing circuit controlled by said bomb button; arranged to open said circuit upon release of said bomb button; and means for restoring both of said intervalometer timing devices to zero when said energizing circuit is opened in which said pull up signal means includes an energizing circuit therefor; relay means for closing said last mentioned circuit and means for energizing the last mentioned relay means from the first mentioned intervalometer at the expiration of its timing cycle.

10. A low altitude aircraft high explosive bombing apparatus for bombing a selected remote target on a bombing run directly toward said selected target which transversely crosses an elongated geographical landmark reference point at a predetermined flight time from the target which is in excess of a predetermined safe escape distance from the target at the time the bomb device is exploded at the target following a pull up and release of the bomb device at a predetermined low altitude, speed, and angle of climb suificient to permit the aircraft to turn and fiy to said safe remote distance from the target by the time the bomb device reaches the target, said apparatus comprising; a bombing aircraft; a high explosive bomb device releasably carried by said aircraft, pull up signal means carried by said aircraft; settable time controlled means carried by said aircraft for operating said pull up signal means to indicate a pull up signal to the operator of said aircraft; settable bomb release means carried by said aircraft for releasing said bomb device during said pull up at a predetermined angle of climb following the actuation of said pull up signal means by said settable time control means, in which said settable time control means includes an intervalometer and manual means for initiating said intervalometer into operation at the instant of crossing said prominent reference point in a bombing run toward the target, including a second settable time controlled intervalometer for exploding said bomb device set for a time period equal to said time of flight from said prominent point to said pull up point plus the time of flight from said pull up point to said release point at said angle of climb at a predetermined number of gs plus the trajectory time of said bomb device from said release point to a burst point at the target including means for simultaneously starting both of said intervalometers including a common intervalometer starting circuit therefor and an energizing bomb button switch for said circuit adapted to be closed by the pilot at the instant of crossing said prominent reference point in a bombing run toward the target including means in said energizing circuit controlled by said bomb button; arranged to open said circuit upon release of said bomb button; and means for restoring both of said intervalometer timing devices to zero when said energizing circuit is opened in which said pull up signal means includes an energizing circuit therefor; relay means for closing said last mentioned circuit and means for energizing the last mentioned relay means from the first mentioned intervalometer at the expiration of its timing cycle in which said settable bomb release means includes a normally caged vertical gyroscope device carried by the aircraft; means for uncaging said gyroscope just prior to crossing said prominent reference point; adjustable bomb release circuit closing contacts carried by said gyroscope adjustable for closing at any predetermined angle of climb of the aircraft; a bomb release circuit including the last mentioned circuit closing contacts; said contacts being angularly spaced and including a first contact adjustably fixed relative to the attitude of the aircraft in pitch and a second cooperating contact fixed in space by the gimbal means of said gyroscope and adapted to contact said first contact when the climb angle of the aircraft reaches the predetermined climb angle for the release of the bomb device; bomb release means; and relay means in said bomb release circuit for actuating said bomb release means when said bomb release circuit is energized; a second relay means in said bomb release circuit normally maintaining said bomb release circuit open; and an energizing circuit for said last mentioned relay means operatively connected to said bomb button energizing circuit for maintaining the bomb device release circuit operative only during the time that the bomb button energizing circuit is closed by said bomb button.

References Cited in the file of this patent UNITED STATES PATENTS 2,609,729 Wilkenson et al. Sept. 9, 1952 2,712,269 Garbarni et a1. July 5, 1955 2,736,878 Boyle Feb. 28, 1956 2,758,511 McLean et al Aug. 14, 1956 2,805,601 Morton Sept. 10, 1957 FOREIGN PATENTS 1,005,077 France Dec. 12, 1951 OTHER REFERENCES Court of Claims of the United States, No. 43,055, Robert V. Morse v. The United States, Report of Con1 missioner.

Aircraft Engineering, September 1942, Notes on Enemy Bombsights, pp. 244-247. 

